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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: OnCreate.html 842 2015-03-07 18:20:42Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.jsimpledb.annotation;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.lang.annotation.Documented;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.lang.annotation.ElementType;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import java.lang.annotation.Retention;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import java.lang.annotation.RetentionPolicy;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import java.lang.annotation.Target;<a name="line.14"></a>
<span class="sourceLineNo">015</span><a name="line.15"></a>
<span class="sourceLineNo">016</span>/**<a name="line.16"></a>
<span class="sourceLineNo">017</span> * Annotates JSimpleDB model class methods that are to be invoked whenever a database object is newly created.<a name="line.17"></a>
<span class="sourceLineNo">018</span> *<a name="line.18"></a>
<span class="sourceLineNo">019</span> * &lt;p&gt;<a name="line.19"></a>
<span class="sourceLineNo">020</span> * Note that there is a subtle distinction between (a) the creation of database objects in the database, and<a name="line.20"></a>
<span class="sourceLineNo">021</span> * (b) the instantiation of Java model objects that represent database objects (i.e., {@link org.jsimpledb.JObject}s).<a name="line.21"></a>
<span class="sourceLineNo">022</span> * These two events do not necessarily always occur at the same time. Methods that are annotated with<a name="line.22"></a>
<span class="sourceLineNo">023</span> * {@link OnCreate &amp;#64;OnCreate} are invoked only for event (a). In particular, Java model objects are often<a name="line.23"></a>
<span class="sourceLineNo">024</span> * instantiated to represent database objects that may not actually exist in the database.<a name="line.24"></a>
<span class="sourceLineNo">025</span> * &lt;/p&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span> *<a name="line.26"></a>
<span class="sourceLineNo">027</span> * &lt;p&gt;<a name="line.27"></a>
<span class="sourceLineNo">028</span> * As a consequence, for any database fields that require default initialization, this initialization should be<a name="line.28"></a>
<span class="sourceLineNo">029</span> * performed not in a Java constructor but rather in an {@link OnCreate &amp;#64;OnCreate}-annotated method. Otherwise,<a name="line.29"></a>
<span class="sourceLineNo">030</span> * {@link org.jsimpledb.core.DeletedObjectException}s (and {@link org.jsimpledb.core.ReadOnlyTransactionException}s<a name="line.30"></a>
<span class="sourceLineNo">031</span> * within read-only transactions) may unexpectedly occur.<a name="line.31"></a>
<span class="sourceLineNo">032</span> * &lt;/p&gt;<a name="line.32"></a>
<span class="sourceLineNo">033</span> *<a name="line.33"></a>
<span class="sourceLineNo">034</span> * &lt;p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span> * For example, instead of this:<a name="line.35"></a>
<span class="sourceLineNo">036</span> * &lt;pre&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> *  &amp;#64;JSimpleClass<a name="line.37"></a>
<span class="sourceLineNo">038</span> *  public abstract class Event {<a name="line.38"></a>
<span class="sourceLineNo">039</span> *<a name="line.39"></a>
<span class="sourceLineNo">040</span> *      protected Event() {<a name="line.40"></a>
<span class="sourceLineNo">041</span> *          this.setCreateTime(new Date());<a name="line.41"></a>
<span class="sourceLineNo">042</span> *      }<a name="line.42"></a>
<span class="sourceLineNo">043</span> *<a name="line.43"></a>
<span class="sourceLineNo">044</span> *      public abstract Date getCreateTime();<a name="line.44"></a>
<span class="sourceLineNo">045</span> *      public abstract void setCreateTime(Date createTime);<a name="line.45"></a>
<span class="sourceLineNo">046</span> *<a name="line.46"></a>
<span class="sourceLineNo">047</span> *      ...<a name="line.47"></a>
<span class="sourceLineNo">048</span> * &lt;/pre&gt;<a name="line.48"></a>
<span class="sourceLineNo">049</span> * do this:<a name="line.49"></a>
<span class="sourceLineNo">050</span> *<a name="line.50"></a>
<span class="sourceLineNo">051</span> * &lt;pre&gt;<a name="line.51"></a>
<span class="sourceLineNo">052</span> *  &amp;#64;JSimpleClass<a name="line.52"></a>
<span class="sourceLineNo">053</span> *  public abstract class Event {<a name="line.53"></a>
<span class="sourceLineNo">054</span> *<a name="line.54"></a>
<span class="sourceLineNo">055</span> *      protected Event() {<a name="line.55"></a>
<span class="sourceLineNo">056</span> *      }<a name="line.56"></a>
<span class="sourceLineNo">057</span> *<a name="line.57"></a>
<span class="sourceLineNo">058</span> *      &amp;#64;OnCreate<a name="line.58"></a>
<span class="sourceLineNo">059</span> *      private void init() {<a name="line.59"></a>
<span class="sourceLineNo">060</span> *          this.setCreateTime(new Date());<a name="line.60"></a>
<span class="sourceLineNo">061</span> *      }<a name="line.61"></a>
<span class="sourceLineNo">062</span> *<a name="line.62"></a>
<span class="sourceLineNo">063</span> *      public abstract Date getCreateTime();<a name="line.63"></a>
<span class="sourceLineNo">064</span> *      public abstract void setCreateTime(Date createTime);<a name="line.64"></a>
<span class="sourceLineNo">065</span> *<a name="line.65"></a>
<span class="sourceLineNo">066</span> *      ...<a name="line.66"></a>
<span class="sourceLineNo">067</span> * &lt;/pre&gt;<a name="line.67"></a>
<span class="sourceLineNo">068</span> *<a name="line.68"></a>
<span class="sourceLineNo">069</span> * &lt;p&gt;<a name="line.69"></a>
<span class="sourceLineNo">070</span> * Notifications are delivered in the same thread that created the object, immediately after the object is created.<a name="line.70"></a>
<span class="sourceLineNo">071</span> * &lt;/p&gt;<a name="line.71"></a>
<span class="sourceLineNo">072</span> *<a name="line.72"></a>
<span class="sourceLineNo">073</span> * &lt;p&gt;<a name="line.73"></a>
<span class="sourceLineNo">074</span> * The annotated method must be an instance method (i.e., not static), return void, and take zero parameters.<a name="line.74"></a>
<span class="sourceLineNo">075</span> * It may have any level of access, including {@code private}.<a name="line.75"></a>
<span class="sourceLineNo">076</span>* &lt;/p&gt;<a name="line.76"></a>
<span class="sourceLineNo">077</span>*/<a name="line.77"></a>
<span class="sourceLineNo">078</span>@Retention(RetentionPolicy.RUNTIME)<a name="line.78"></a>
<span class="sourceLineNo">079</span>@Target(ElementType.METHOD)<a name="line.79"></a>
<span class="sourceLineNo">080</span>@Documented<a name="line.80"></a>
<span class="sourceLineNo">081</span>public @interface OnCreate {<a name="line.81"></a>
<span class="sourceLineNo">082</span><a name="line.82"></a>
<span class="sourceLineNo">083</span>    /**<a name="line.83"></a>
<span class="sourceLineNo">084</span>     * Determines whether this annotation should also be enabled for<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * {@linkplain org.jsimpledb.SnapshotJTransaction snapshot transaction} objects.<a name="line.85"></a>
<span class="sourceLineNo">086</span>     * If unset, notifications will only be delivered to non-snapshot (i.e., normal) database instances.<a name="line.86"></a>
<span class="sourceLineNo">087</span>     *<a name="line.87"></a>
<span class="sourceLineNo">088</span>     * @return whether enabled for snapshot transactions<a name="line.88"></a>
<span class="sourceLineNo">089</span>     * @see org.jsimpledb.SnapshotJTransaction<a name="line.89"></a>
<span class="sourceLineNo">090</span>     */<a name="line.90"></a>
<span class="sourceLineNo">091</span>    boolean snapshotTransactions() default false;<a name="line.91"></a>
<span class="sourceLineNo">092</span>}<a name="line.92"></a>
<span class="sourceLineNo">093</span><a name="line.93"></a>




























































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